This multithreaded Geant4 program simulates a ³He counter tube for thermal and epithermal neutron detection. The detector simulated is the VacuTec 70063 proportional counter with 4bar pressure. Datasheet: https://www.vacutec-gmbh.de/fileadmin/VacuTec-Files/produkte/umwelt/Zaehlrohre__GM-__P-__N-_/Neutronen_Zaehlrohre/He-3_NEUTRON_DETECTORS_flyer_710_3.pdf
The world is a Box filled with Air at 1 bar pressure.
Inside of the world volume is the ³He counter tube (G4Tubs) which has following components asigned to his volume:
- Stainless steel wall (AES 304 stainless steel)
- Active detector Gas (³He, 4bar pressure)
- Currently only as comment: Anode wire in the middle of the tube with diameter 100um
The detector measurements can be changed in the DetectorConstruction.hh header file
The PhysicsList implements builders for:
- Hadronic elastic physics
- Hadronic inelastic physics (QGSP_BIC_HP)
- Ion elastic physics
- Ion inelastic
- EM physics
- Gamma nuclear physics
Primary particle: neutron
Default energy: 25 meV (thermal neutrons)
Each event is 1 neutron with momentum in negative x direction pointing towards the
³He volume of the counter tube.
Two options for the position of the particle gun are available (both are in the PrimaryGeneratorAction.cc file, one option is always commented):
- Neutron bombardment over the full length and height of the counter tube
- Focused neutron beam with round cross sectional area
Goal of each run of n events is to:
- Store all reaction points of the n + ³He -> p + ³H process in the counter tube
- Calculate the ³He inelastic cross section and compare it with the G4HadronicProcessStore which has its cross section data from the ENDF (https://www-nds.iaea.org/exfor/endf.htm) libary.
- Get the total number of the previous mentioned process
- Get the number of neutrons passing the counter tube
- List all hadronic processes with the counter tube (wall + gas)
- List all produced particles through inelastic processes
- Get the energy distribution of the proton and the triton
- To see the wall effect: Get the energy deposit of the secondary particles for each inelastic event in the counter tube.
- Study detection efficiency
1, 4, 7 and 8 are saved to a root file with the default name hits.root. It is possible to change the filename via /analysis/setFileName in the geant4 interactive mode.
The cross section information is added to the output file crossSection.txt.
The detection efficiency data is stored in the output file data.txt
The complete output of the program (detector efficiency data, nuclear reactions, cross section, produced particles) gets written to the output file output.txt.
If you dont have geant4 installed: https://geant4.web.cern.ch/download/10.7.4.html
To build the application:
- Create a build directory in the program folder
- Go to the build directory and execute:
cmake ..- Build the program:
make- Run the executable NeutronDet
To start the application:
- After starting the application it is necessary to initialize the Geant4 kernel with the interactive command /run/initialize.
- Optionally: you can change the name of the root output file with the interactive commmand /analysis/setFileName
- Create a run with the interactive command /run/beamOn
The above mentioned commands are only necessary if you dont use one of the 3 provided macro files which are explained in the next section.
There are also 3 macro files provided:
- vis.mac (to visualize the geometry)
- crossSectionAnalysis.mac (creates various runs of 10^5 neutrons with different energies. The energy dependent cross section can then be plotted using the crossSection.txt file)
- hitsAnalysis.mac (creates various runs of 10^5 neutrons with different energies. Before each run it creates a new root file with the following name: "hits__.root")
All the macro files can be used with the command /control/execute